title: The production of volvox spheres and their potential application in multi-drugs encapsulation and release.
abstract: Volvox sphere is a bio-mimicking concept of an innovative biomaterial structure of a sphere that contains smaller microspheres which then encapsulate chemicals, drugs and/or cells. The volvox spheres were produced via a high-voltage electrostatic field system, using alginate as the primary material. Encapsulated materials tested in this study include staining dyes, nuclear fast red and trypan blue, and model drugs, bovine serum albumin (BSA) and cytochrome c (CytC). The external morphology of the volvox spheres was observed via electron microscopy whereas the internal structure of the volvox spheres was observed via an optical microscope with the aid of the staining dyes, since alginate is colorless and transparent. The diameter of the microspheres was about 200 to 300 μm, whereas the diameter of the volvox spheres was about 1500 μm. Volvox spheres were durable, retaining about 95% of their mass after 4 weeks. Factors affecting entrapment efficiency, such as temperature and concentration of the bivalent cross-linker, were compared followed by a 7-day in vitro release study. The encapsulation efficiency of CytC within the microspheres was higher at cold (~4°C) and warm (~50°C) temperatures whereas temperature has no obvious effect on the BSA encapsulation. High crosslinking concentration (25% w/v) of calcium chloride has resulted higher entrapment efficiency for BSA but not for CytC. Furthermore, volvox spheres showed a different release pattern of BSA and CytC when compared to microspheres encapsulating BSA and CytC. Despite the fact that the mechanisms behind remain unclear and further investigation is required, this study demonstrates the potential of the volvox spheres for drug delivery.
authors.affiliation: Department of Biomedical Engineering, I-Shou University, College of Medicine, No. 8, Yida Rd., Jiaosu Village, Yanchao District, Kaohsiung City 82445, Taiwan.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Teong
authors.forename: Shwu Jen
authors.initials: SJ
authors.lastname: Chang
authors.forename: Chin Wen
authors.initials: CW
authors.lastname: Chuang
authors.forename: Shyh Ming
authors.initials: SM
authors.lastname: Kuo
authors.forename: Ioannis
authors.initials: I
authors.lastname: Manousakas
mesh_terms: D000464:Alginates / Q000737:chemistry; D000818:Animals; D040761:Biomimetic Materials / Q000737:chemistry*; D002122:Calcium Chloride / Q000737:chemistry; D002417:Cattle; D004396:Coloring Agents / Q000737:chemistry; D045304:Cytochromes c / Q000737:chemistry* / Q000378:metabolism; D004337:Drug Carriers / Q000737:chemistry; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D008863:Microspheres; D010316:Particle Size; D012710:Serum Albumin, Bovine / Q000737:chemistry* / Q000378:metabolism; D013696:Temperature
chemical_list: D000464:Alginates; D004396:Coloring Agents; D004337:Drug Carriers; D006603:Hexuronic Acids; D012710:Serum Albumin, Bovine; D020723:Glucuronic Acid; D045304:Cytochromes c; D002122:Calcium Chloride
keywords: Alginate; Drug delivery system; High-voltage electrostatic field; Microsphere; Volvox sphere